Triethylamine → 1,8-Diazabicyclo(5.4.0)undec-7-ene

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Reaction Steps

3-Chloropropanesulfonyl chloride (4.58 mL, 37.7 mmol) was added dropwise to a solution of 4-[7-(benzyloxy)-2-(ethoxymethyl)-1H-imidazo[4,5-c]quinolin-1-yl]butan-1-amine dihydrochloride (12.1 g, 25.3 mmol) and triethylamine (14.0 mL, 101 mmol) in dichloromethane (168 mL) at room temperature. The solution was stirred for 17 hours, then transferred to a separatory funnel and washed with 5% aqueous sodium carbonate, water, and saturated aqueous sodium chloride. The organic layer was dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure. The residue was dissolved in DMF (168 mL) and treated with 1,8-diazabicyclo[5.4.0]undec-7-ene (5.70 mL, 38 mmol). The solution was stirred for 40 hours, then the DMF was removed under reduced pressure. The residue was dissolved in dichloromethane and washed repeatedly with water then saturated aqueous sodium carbonate. The organic layer was dried over anhydrous sodium sulfate, filtered, and evaporated to afford 7-(benzyloxy)-1-[4-(1,1-dioxidoisothiazolidin-2-yl)butyl]-2-(ethoxymethyl)-1H-imidazo[4,5-c]quinoline in almost quantitative yield with some residual 1,8-diazabicyclo[5.4.0]undec-7-ene as a brown oil, which was used without further purification.

Provenance & Evidence